Many types of injuries and surgeries can result in an individual losing some range of motion in his or her knee joint. For example, patients who undergo surgery to treat anterior or posterior cruciate ligament reconstructions, meniscus tears, femur fractures, tibia plateau fractures, or other injuries associated with the knee joint or nearby areas of the body often experience some degree of arthrofibrosis (joint stiffness). Indeed, arthrobrosis is one of the leading complications of knee surgery. This undesirable condition results from the formation of extensive, internal scar tissue and other factors that limit motion of the patient's knee joint. Arthrofibrosis may involve the loss of flexion (bending movements), the loss of extension (straightening movements), or both.
To treat arthrofibrosis, a patient must typically follow a specially planned, intensive protocol of serial stretching and overpressure therapy. This protocol is primarily carried out through hands-on treatment from a physical therapist in a clinic. Although physical therapy may help the patient regain partial or full range-of-motion, the closely-supervised treatment can be relatively expensive and inconvenient for the patient. Several physical therapy sessions are often required each week to treat arthrofibrosis, which means that the patient must adjust his or her schedule accordingly.
As a result, some orthopedic surgeons recommend using in-home mechanical therapy devices as an alternative to (or to decrease reliance on) hands-on physical therapy. Several mechanical devices have been developed to stretch a patient's knee joint and thereby urge increased motion. Current devices, however, leave significant room for improvement.
For example, many of the current in-home mechanical therapy devices are complex to operate, involve numerous parts, or have limited effectiveness. These devices may require the patient to actuate levers, stabilize components, or perform other functions while attempting to stretch his or her knee joint, which may be a painful process that requires concentration itself. Moreover, many of the in-home mechanical devices are not designed to stretch the knee joint in both flexion and extension. The use and storage of two separate devices to treat joint stiffness can be cumbersome.
Although automated continuous passive motion (CPM) machines exist for more effectively stretching knee joints and other areas of the body, these machines are not designed for in-home use. In particular, these machines typically include a mechanical leg cradle that bends and straightens the patient's knee while the patient sits or lies down on a supporting surface. Machines including the supporting surface occupy a significant amount of space and are intended for facilities dedicated to treatment (physical therapy facilities, etc.), which have the space to accommodate such machines. The machines are also relatively expensive because of their complexity.
For at least these reasons, a mechanical therapy device that effectively stretches a patient's knee joint and that is suitable for in-home use would be highly desirable.